Why don't we hear about recycling energy?

Answer 1

Because by its nature energy cannot be recycled.

Energy can only be converted from one form to another and each time energy is used the resulting form is more diffuse and harder to extract further energy from. Ultimately the energy is completely dissipated and unusable.

Answer 2

The "R" associated with energy is either Reduction or Recovery:

• Reducing energy requite using less or
• using it more efficiency or
• using a lesson[actul source
  

Recovery includes:

• Using waste heat streams to provide heat to subsequent uses or
  
• recovering waste for energy (fuel)